Container: Add initial container for meshtastic-cli

Just a quick set of files to enable the build of (tagged) containers.
Both alpine and debian containers are available (~200MiB/~1.2GiB)
allowing us to use meshtastic cli with a quick docker run, instead of
having to build/install stuff locally.

Signed-off-by: Olliver Schinagl <oliver@schinagl.nl>

bin/container-entrypoint.sh

@@ -0,0 +1,24 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-3.0-or-later
+#
+# Copyright (C) 2025 Olliver Schinagl <oliver@schinagl.nl>
+#
+# A beginning user should be able to docker run image bash (or sh) without
+# needing to learn about --entrypoint
+# https://github.com/docker-library/official-images#consistency
+
+set -eu
+
+bin='meshtastic'
+
+# run command if it is not starting with a "-" and is an executable in PATH
+if [ "${#}" -le 0 ] || \
+   [ "${1#-}" != "${1}" ] || \
+   [ -d "${1}" ] || \
+   ! command -v "${1}" > '/dev/null' 2>&1; then
+	entrypoint='true'
+fi
+
+exec ${entrypoint:+${bin:?}} "${@}"
+
+exit 0